644869085 has 16 divisors (see below), whose sum is σ = 914889600. Its totient is φ = 426947136.

The previous prime is 644869067. The next prime is 644869103. The reversal of 644869085 is 580968446.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (644869067) and next prime (644869103).

It is not a de Polignac number, because 644869085 - 2²⁰ = 643820509 is a prime.

It is a super-2 number, since 2×644869085² = 831712273577474450, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 316655 + ... + 318684.

It is an arithmetic number, because the mean of its divisors is an integer number (57180600).

Almost surely, 2^644869085 is an apocalyptic number.

It is an amenable number.

644869085 is a deficient number, since it is larger than the sum of its proper divisors (270020515).

644869085 is a wasteful number, since it uses less digits than its factorization.

644869085 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 635380.

The product of its (nonzero) digits is 1658880, while the sum is 50.

The square root of 644869085 is about 25394.2726810594. The cubic root of 644869085 is about 863.9537999166.

The spelling of 644869085 in words is "six hundred forty-four million, eight hundred sixty-nine thousand, eighty-five".